the airbag system is designed for a TJ... you could design a link suspension to run it, but why not just run coilovers (expensive) or 1/4 elliptic springs (cheap) in the rear if you're going to bother with a linked suspension? sticking an airbag between your frame and leaf spring isn't going to improve your articulation any...
personally if you want more flex, SOA your front leafs and do a 4 link with 1/4 elliptical springs... avalanche has an overpriced kit for this at http://www.avalancheengineering.com/suspensionellip.htm
or you can piece together rodends, spuds, jam nuts and some 1.5 .250 wall DOM, brackets and do it yourself... you need welding and fabrication knowledge
take it easy
00 Lexus GS300
97 Suburban 6.5 Turbo Diesel 6" lift 35" BFG A/Ts
81 CJ-7 rock buggy, injected 350, built th350, 3.8 atlas II w/ ebrake, d60 front 1.5 stubs w/ detroit, 4.88 gears, discs, d70 rear w/ detroit, 4.88 gears, discs, 37" krawlers, 17" trailready beadlocks, 16" king coilovers, 4 link f/r, 12+ point cage, howe full hydraulic steering, fabbed by owner :D